Box and blank made from cardboard sheet with convex centring devices

ABSTRACT

A box and a blank or a set of blanks made from corrugated cardboard sheet comprising side walls, a top wall linked to at least two of said opposing side walls by a junction line or a folded edge, and a bottom wall forming the bottom of the box. The top wall comprises at least two convex portions comprising a projecting part, and the bottom comprises at least two perforated surface portions of complementary shape arranged to engage with the projecting parts of the box below. Each convex portion comprises an oblique triangular or substantially triangular panel belonging partly to a side wall or a folded edge.

The present invention relates to a box made from corrugated cardboardsheet material of the type comprising a top wall formed by flaps, ledgesor ledge portions or, furthermore, a lid, with convex centering devicesand a bottom wall with recesses so as to complement the form of theconvex portions.

It also relates to a blank or set of blanks for making up such a box.

It further relates to a method for manufacturing such a box with convexcentering devices.

It is particularly widely used, albeit not exclusively, in the field ofboxes that can be stacked on a pallet, which may tend to slide over oneanother when handled during the transportation phase.

Box centering systems that make it possible to prevent their sliding,using vertically cut out side pegs that interact with orifices placed onthe ridges, or in the vicinity, are already known.

Such systems are fragile, are unsuitable for sheet materials with a lowweight per unit area, and do not withstand repeated handling.

Also known (FR 2 990 416) are boxes of the type mentioned above in whichthe top wall comprises convex portions cut out entirely from said walland linked to the adjacent side face by a non-rectilinear junction linein order to form a deformable side that rises up upon folding.

Although this offers the advantage of it being possible to use such asystem with sheet materials with a low weight per unit area, it doesnot, in particular, allow a great deal of engagement, which may beproblematic in the case of merchandise that is shaken to any greatextent.

In point of fact, new regulatory constraints aimed at ensuring bettersecuring of transported loads are currently in preparation.

These relate, in particular, to the stability of packages on pallets,and are intended to set limits on the sliding of loads stacked insuperposed layers at the time of braking and/or acceleration occurringduring transportation.

The present invention aims to provide a box, a blank or set of blanksand a method for manufacturing a box made from corrugated cardboardsheet which fulfils practical requirements better than boxes knownhitherto, in particular in that it allows, for all packagingconfigurations (crates, trays with ledges, lidded trays, wrap), completestability of the layers of boxes stacked one upon another on a pallet,with excellent alignment of the bearing walls. The dimensions of thecentering elements, which are formed automatically without gluing, can,furthermore, be easily calculated and/or adjusted as a function of theloads envisaged in the box and the constraints imposed by regulations.

With the invention, it will thus be possible to limit the risks offalling when truck doors are opened and pallets are handled, accountbeing taken of the weight of the transported products, which makes itpossible, therefore, to optimize the actual packaging.

The invention in fact allows a reduction in inter-layer slidingphenomena on account of better engagement of packages with one another,it being possible, in particular, for the convex parts to be dimensionedspecifically and adapted to each type of load.

Compression strength may thus be minimized and the fibrous compositionof the packaging optimized, while guaranteeing satisfactory behaviour ofpackages vis-à-vis one another.

The simple form of the centering system further makes it possible for itto be positioned on partially cut out American cases. It can be adaptedto packaging lines already in place, without the addition of a gluingdevice.

The elasticity of the centering device enables it temporarily towithstand the horizontal pressure bands commonly found on flap closuremachines. The assembly is, furthermore, compatible with an adhesive bandflap closure.

Lastly, it can be used on any type of packaging geometry provided thereis a 90° overlap of a flap, edge or ledge.

To this end, the present invention proposes, in particular, a box madefrom corrugated cardboard sheet material having a polygonal section,comprising side walls, a top wall linked to at least two of saidopposite side walls by a junction line or a folded edge, and a bottomwall forming the bottom of the box, the top wall comprising at least twoconvex portions each comprising a part projecting from the surface ofsaid top wall and the bottom comprising at least two portions with asurface perforated so as to complement said projecting parts, in linewith the latter and arranged in order to engage in the projecting partsof the box below, characterized in that each convex portion comprises anoblique triangular or substantially triangular panel belonging partly toa side wall or a folded edge.

“Substantially triangular panel” is understood to mean a triangularpanel comprising at least one side that may not be rectilinear (curved,for example concave).

“Oblique” is understood to mean oblique relative to the vertical planeof the side walls or relative to the horizontal plane of the top wall ortop of the box.

“Convex portion” is understood to mean, in particular, a portion that isnot solely located in one and the same plane and, in the present case,in the same plane as the external face of the top wall of the box.

In the present case, the part projecting from the top surface of the boxof the convex portion will form the centering system, which, on accountof the triangular or substantially triangular panel, will rise upautomatically upon 90° folding of the flaps, edges or ledge portions.

On account of the third fold line or crease that is offset relative tothe junction line of the top wall with the corresponding side wall, thematerial of the flap automatically stands up upon folding in order tocreate an extra thickness.

When two boxes are stacked on one another, the extra thickness ispositioned in the perforated surface portions or openings provided inthe bottom (flaps, or central sheet) of the box placed above.

With the invention, the centering element or centering device is thusformed from a portion of deformable material of trapezoidal overallshape, a part of which (the triangular panel) straddles a vertical wallof the box, the other part extending flat above, and two adjacent sidesof which are cut out so as to allow same to rise up, while the other twosides are linked to the body of the packaging by fold lines or creasedfolds.

Rising is obtained automatically when the flap is folded at 90°, aportion of the centering device being forced to form an angle with thevertical on account of the triangular double fold.

As a function of the angle alpha formed between the triangle or obliquepanel and the external face of the top wall, and also the distances ofsection A (in the side face) and B (in the top face), the projectingpart is:

-   -   offset more or less toward the interior of the packaging;    -   more or less able to withstand vertical crushing and thus more        or less elastic, which is of major interest in the case of a        crossed-layer stack;    -   more or less prominent (rise height).

Thus, for one and the same rise height, there are a plurality ofsolutions of combinations of angles alpha, of length of sections A andB, which may thus be determined as a function of the centering effectsought, the desired elasticity and the resistance to flattening of thecentering device, as will be further specified below with reference tothe figures.

In other words, it is possible to adjust these parameters, particularlyas a function of the other features of the box (cardboard thickness,quality, etc.) and of the load it is to contain, doing so in order tocomply with imposed constraints on sliding/non-sliding.

In advantageous embodiments, recourse is, furthermore and/or moreoverhad to one and/or to another of the following arrangements:

-   -   each convex portion has four sides, namely two adjacent sides        that are free or cut out from the top wall, the other two,        opposite sides being, respectively, linked to the top wall by a        first fold line and to the adjacent side wall or to the folded        edge by a second fold line that is oblique toward the bottom of        the box, and further comprises a third fold line, that is        oblique and has a summit common with the first and second fold        lines, in order to form the triangular or substantially        triangular panel;    -   the third fold line is curved. Advantageously, it is concave;    -   the box forms a rectangular tray with ledge portions located at        the four corners of the tray, which are symmetrical relative to        the transverse axis of the tray, each ledge portion being formed        by a flap having an end part forming the projecting part of the        convex portion and by a median part linked to a tongue for        fastening on the facing side wall adjacent the wall linked to        the ledge portion;    -   the side walls form a belt and the top wall is formed by two        flaps linked to two opposite walls by said junction lines;    -   the box is in the form of a rectangular tray and the top wall is        formed by a lid provided with folded edges glued onto the        external faces of the facing side walls after folding of the        junction lines with the edges;    -   the oblique panel forms an angle alpha with the top face of the        box of between 40° and 55°;    -   the top wall is a principal sheet of a wrap belt and the side        walls are formed partly by flaps linked to said sheet by said        junction lines.

The invention also proposes a blank or set of blanks that make itpossible to obtain a box as described above.

It also proposes a blank or set of blanks made from corrugated cardboardsheet material intended for forming a box with a polygonal sectioncomprising side walls, a top wall linked to two of said opposite sidefaces by a junction line, and one or more bottom faces forming thebottom of the box, characterized in that the top wall is formed by apair of flaps, a pair of ledge portions, a lid with edges, or a wrapsheet, and comprises at least two portions each provided with an obliquesubstantially triangular panel belonging partly to a side wall or to anedge, straddling the junction line between walls or wall and edge, andcapable of forming a convex portion creating a part projecting from thetop surface of the box when the box is formed, and the bottom comprisesat least two portions with a perforated surface so as to complement saidprojecting parts when they are formed, in line with the latter when thebox is formed and arranged in order to engage in the projecting parts ofa box below.

Advantageously, each portion capable of forming a convex portion hasfour sides, namely two adjacent sides that are free or cut out from thetop wall, the other two, opposite sides being, respectively, linked tothe top wall by a first fold line and to the side wall or to the edge ofthe lid by an oblique second fold line, and further comprises a thirdfold line that is oblique and has a summit common with the first andsecond fold lines, in order to form the triangular or substantiallytriangular panel.

Likewise, advantageously, the third fold line is curved, andadvantageously concave with a concavity corresponding to a radius ofcurvature of between 20 cm and 80 cm.

In an advantageous embodiment, the blank is capable of forming arectangular tray with ledge portions located at the four corners of thetray, which are symmetrical relative to the transverse axis of the tray.

Each ledge portion is formed by a flap having an end part forming theprojecting part of the convex portion and by a median part connected toa tongue for fastening on the facing side wall when the box is formed.

Likewise, advantageously, the third fold line or the tangent to thesummit of the third fold line forms an angle beta with the junction lineof between 15° and 45°.

The invention also proposes a method for manufacturing a box asdescribed above.

The invention will be better understood upon reading the followingdescription of embodiments given below by way of non-limiting examples.The description makes reference to the drawings that accompany it, inwhich:

FIG. 1 is a perspective view of a box according to a first embodiment ofthe invention.

FIGS. 1A and 1B are perspective front and rear views of a convexcentring device of FIG. 1.

FIG. 1C is a section on Ic-Ic of the convex portion of FIG. 1A.

FIG. 1D is a flattened view of the convex portion before folding of theflap at 90°.

FIG. 2 is a perspective view showing two boxes according to FIG. 1engaging in one another.

FIG. 3 is a plan view of the blank that makes it possible to obtain thebox of FIG. 1.

FIG. 4 shows a graph giving the values of the section dimensions A and B(cf. FIG. 1A) and of the angle α as a function of a fixed height of theconvex centring device (in this case, 10 mm) relative to the top face ofthe top wall.

FIG. 5 is a perspective view of a box according to a second embodiment,in the form of a tray with ledge portions.

FIG. 6 is a plan view of the blank that makes it possible to obtain thebox of FIG. 5.

FIG. 7 is a perspective view of a third embodiment of a box according tothe invention, in wrap form.

FIG. 8 is a plan view of the blank of the box in FIG. 7.

FIGS. 9A and 9B show plan views of a set of blanks for forming a boxwith a lid, according to a fourth embodiment of the invention.

FIG. 1 shows a parallelepipedal box 1 made from corrugated cardboardsheet, for example double-face cardboard sheet that is 3 mm thick.

The box 1 comprises a belt 2 of rectangular side walls 3, 4, 5, 6, a topwall 7 formed by two rectangular flaps 8, 9 contiguous at their ends 10,linked to two corresponding side walls 3, 5 by opposite junction lines11, 12 and a bottom wall 13 (see FIG. 2) forming the bottom of the box.

The top wall comprises four convex portions 14 (cf., also, FIGS. 1B, 1Cand 1D) each comprising a part 15 projecting from the external face ofthe top wall.

The bottom wall 13 is also formed by two opposite flaps 16 and 17,contiguous at their ends and comprising, for each of the flaps, twoperforated surface portions 18 arranged so as to engage with theprojecting parts 15′ of the box 1′ below (see FIG. 2) and having, in thepresent case, a trapezium shape, possibly with an angle at the inclinedbase of a few degrees in the same direction.

Each convex portion 14, 14′ comprises a triangular or substantiallytriangular panel 19, 19′ belonging partly to an adjacent side wall 3,3′, 5, 5′.

More precisely, with reference to FIGS. 1A, 1B, 1C and 1D, each convexportion 14 is of generally trapezoidal shape and comprises four sides,namely two adjacent sides 20, 21 cut out in the flap 8 of the top wall,the other two sides 22, 23 being, respectively, linked to the top wall 8by a first fold line 24 partially perforated in order to allow reversefolding of the projecting part of the centering device, and to theadjacent wall 3 by a second fold line 25 that is oblique toward thebottom (arrow 26) of the box.

The convex portion 14 further comprises a third oblique fold line 27,which is concave and has a summit 28 common with the first and secondfold lines 24 and 25 in order to form the diamond-like triangular panel19.

In this embodiment, the oblique panel 19 forms an angle α with the topface 7 (flap 8) of the box of 60°.

Mechanically, the convex portion will undergo slight twisting at thepoint P at the time of rising (cf. FIG. 1D).

The point P will then move laterally toward the interior of the surfaceof the case.

According to the embodiment of the invention more particularly describedhere, it is assumed here that this point P rises strictly verticallyupon folding of the flap, at a distance B from the vertical edge of thecase, which allows a simple mathematical equation for determining A andB (thus, A+B, which is the necessary sizing dimension), this being as afunction of the angle α sought and of the rise height H.

In this case, there is the following equation: tangent (alpha)=(A+H)/B,which gives excellent sizing, as will be seen precisely below withreference to FIG. 4.

FIG. 3 shows the blank 29 that makes it possible to obtain the box ofFIG. 1.

It is formed from the belt 2 comprising the four side walls 3, 4, 5, 6in the form of rectangular sheets linked by mutually parallel fold lines30. The belt 2 ends in a gluing tongue 31 in a manner known per se.Advantageously, the box is formed around a mandrel, which allows it tobe perfectly square and permits, as a result, faultless alignment andengagement between projecting parts 15 and recesses 18.

Each wall 3 and 5 is linked to the corresponding flaps 8 and 9 (providedwith the centering devices), on the one hand, by a junction line 11 and12, and on the other to the flaps 16, 17 provided with the recesses 18by fold lines 32.

Flaps 33 are linked on either side to the walls 4 and 6 in a mannerknown per se in order to form the interior, at least in part, of the topface of the box.

As indicated above, the centering system is formed automatically upon90° folding of the flaps 8, 9 owing to the diamond shape, the tangent Tat the summit 28 of the third fold line 27 being, for example, an angleβ of 20′.

With the invention, it will be possible to precisely and adjustably sizethe height of the projecting part 15 or height of the centering device.

One of the advantages of the system is, moreover, that it makes itpossible, as a function of the angle α and of the section parameters Aand B, to arrange for the projecting part of the centering device to bemore or less distant (distance x=B) from the vertical side wall of thebox, which makes it possible to conserve more or less material betweenthe exterior edge of the perforated part receiving the projecting partand said edge, and thereby to avoid the start of tearing.

FIG. 4 shows the values of the dimensions A (abscissa), B (ordinate) andangle α as a function of the centering height H, in this case taken inthe example to be 10 mm (cf. FIG. 1A) (cf. curves 34 and 35).

More precisely, for a given height, for example, H=10 mm, and a givensection A, the value of B and of the angle alpha on the curves accordingto the equation defined above result automatically. For manufacturingreasons (difficulty in forming creases that are too close together), avalue A+B greater than 6 or 8 mm will be sought.

It will be seen that there is a plurality of possible solutions of (A)and (B) pairs for the same rise height, the angle alpha depending oneach of the pairs.

The designer will thus have to select, on the graph, the correct (A) and(B) pair to suit whether he wishes to prioritize an offset (B) that ismore or less great or, on the contrary, to prioritize the angle alpha.

In Table I below, for a required height of 10 mm, if the designerdesires a solution with an angle alpha close to 40° in order to obtainsignificant elasticity the only solution is to fix (A) at 5.6 mm andthus (B) will be equal to 19 mm. The leading edge of the centering tabwill thus be offset at 19 mm from the vertical edge of the case.

If the designer wishes above all else that the offset (B) should notexceed 15 mm, while the value of the vertical section (A) should be 10mm and the angle alpha will be 53°, he will thus have less elasticity atthe time of vertical crushing of the tab (by a roller closing the tabsby gluing, for example).

Obviously, a person skilled in the art will without difficulty selectother heights.

The values of the curves are likewise given by way of example in Table Ibelow, the values of A, B and H being expressed in mm.

Furthermore, and for structural reasons, the following values are chosenadvantageously and by way of example:

A+B mini: 8 mm, A mini: 2 mm, α mini=40° and α maxi: 55°.

TABLE I H A B Alpha 10 50.0 11 80° 25.0 12 71° 16.7 13 64° 12.5 14 58°10.0 15 53° 8.3 16 49° 7.1 17 45° 6.3 18 42° 5.6 19 39° 5.0 20 37° 4.521 35° 4.2 22 33° 3.8 23 31° 3.6 24 29° 3.3 25 28° 3.1 26 27° 2.9 27 26°2.8 28 25° 2.6 29 24° 2.5 30 23° 2.4 31 22° 2.3 32 21° 2.2 33 20° 2.1 3420° 2.0 35 19°

In the remainder of the description, use will be made of the samereference numbers to denote the same elements or similar elements.

FIGS. 5 and 6 show, respectively, a tray 36 and the blank 37 that makesit possible to obtain the tray.

In this case, the top wall 7 is formed by ledge portions 38 located atthe four corners of the tray, which are symmetrical relative to thetransverse axis 39 of the tray.

Each portion 38 is formed by a flap 40 having an end part 41 forming theprojecting part 15 of the convex part, as described above (triangle 19,etc.) and by a median part 42 linked to a tongue 43 by a fold line 44,for fastening on the side wall 4, 6 adjacent to the wall 3, 5 linked tothe ledge portion 38 by the junction line 11, 12.

The tray is, furthermore, formed in a manner known per se with arectangular sheet forming the bottom 45 provided with recesses 18,respectively located at the distance x=B from the corresponding walls,and determined as described above.

The other two, opposite side walls are formed by the flaps 46 linked tothe central sheet 45 by fold lines and by the lateral flaps 47 attachedto the walls 3 and 4 and folded down/glued onto the internal face of theflaps 46, in a manner known per se.

FIG. 7 shows a box 50 formed from the wrap 51 of FIG. 8 provided withthe convex centering devices 14.

The blank is formed by a belt 52 of sheets 53, 54, 55, 56, the wall 53comprising the convex centering devices and the wall 55 the recesses 18located at the distance x=B from the junction line 57 between the sheets55 and the rectangular flaps 58, in line with said convex elements.

The centering devices or convex elements 14 are, in the meantime, on thesheet 53, straddling the junction lines 12, as described above, with theflaps 59.

FIGS. 9A and 9B, in the meantime, show, in top view, the blank 60forming a tray in a manner known per se, with a rectangular centralsheet 61 and rectangular lateral flaps 62 attached by fold lines 63 tosaid sheet.

Each flap 62 comprises on either side end flaps 64 arranged in order tobe glued onto the external or internal face of the adjacent flap 65, ina known manner.

The recesses 18 are close to the fold lines 63 in the sheet 61.

FIG. 9B shows the lid 66 comprising a central sheet 67 provided withconvex centering devices 14 straddling the junction lines 68 between theflaps 69 to be folded down and said sheet 67. The sheet 67 alsocomprises, on its two opposite sides, edges 70 with end tongues 71 forachieving the lid once folded down.

A description will now be given of the implementation of the process andof the method corresponding to the invention described moreparticularly, especially with reference to FIGS. 1, 1A and 1B.

On the basis of a specific load, weight per unit area and box size, thedesired engagement height H and the acceptable distance x aredetermined. Then, by means of simple calculation and triangulation, thevalues A and B and the angle α to be selected are determined, by virtue,in particular, of curves of the type described with reference to FIG. 4.

Next, using a blank made from sheet material of the type described withreference to FIG. 3, said blank is rolled around a packaging mandrel.This packaging will then be filled with a product prior to the flapsbeing folded over.

In a first stage, the interior flaps 33 are folded down, and then thetop flaps 8 and 9 are folded down about their junction lines 11 and 12.When the junction line has been folded, the convex centering devicesthen automatically stand up owing to the triangular part. The projectingparts of height H located at the distance x from the edges are thenformed.

The flaps having had glue applied previously onto their internal facethus make it possible to fully form the top face 7.

Next (cf. FIG. 2), the cases will be stacked, the recesses of the topcases being engaged in the convex centering devices of the bottom casesso as to obtain a stack of boxes that is perfectly square, one in linewith the other, and engaged so as to prevent any sliding should thestack be placed at an angle when stresses likely to arise duringtransportation occur.

As is obvious and also follows from the aforesaid, the present inventionis not limited to the embodiments more particularly described. Itencompasses, on the contrary, all variants thereof and, in particular,those in which the recesses comprise at least one rounded angle or areof rectangular or square shape.

1. A box made from corrugated cardboard sheet material having apolygonal section, comprising: side walls; a top wall linked to at leasttwo of said opposite side walls by a junction or a folded edge; and abottom wall forming the bottom of the box, the top wall comprising atleast two convex portions comprising a part projecting from the surfaceof said top wall and the bottom comprising at least two portions with asurface perforated so as to complement said projecting parts, in linewith the latter and arranged in order to engage in the projecting partsof the box below, wherein each convex portion comprises an obliquetriangular or substantially triangular panel belonging partly to a sidewall or a folded edge.
 2. The box as claimed in claim 1, wherein eachconvex portion has four sides, including two adjacent sides that arefree or cut out from the top wall, the other two, opposite sides being,respectively, linked to the top wall by a first fold line and to theadjacent side wall or to the folded edge by a second fold line that isoblique toward the bottom of the box, and in that it further comprises athird fold line, that is oblique and has a summit common with the firstand second fold lines, in order to form the triangular or substantiallytriangular panel.
 3. The box as claimed in claim 2, wherein the thirdfold line is curved.
 4. The box as claimed in claim 1, wherein theoblique panel forms an angle alpha with the top face of the box ofbetween 40 and 55 degrees.
 5. The box as claimed in claim 1, wherein theside walls form a belt, and in that the top wall is formed by two flapslinked to two opposite walls by said junction lines.
 6. The box asclaimed in claim 1, in the form of a rectangular tray, wherein the topwall is formed by a lid provided with folded edges glued onto theexternal faces of the facing side walls after folding of the edges. 7.The box as claimed in claim 1, in the form of a rectangular tray,wherein the top wall being formed by ledge portions located at the fourcorners of the tray, which are symmetrical relative to the transverseaxis of the tray, each ledge portion is formed by a flap having an endpart forming the projecting part of the convex portion and by a medianpart linked to a tongue for fastening on the facing side wall adjacentthe wall linked to the ledge portion.
 8. The box as claimed in claim 1,wherein the top wall is a principal sheet of a wrap belt and the sidewalls are formed partly by flaps linked to said sheet by said junctionlines.
 9. A blank or set of blanks made from corrugated cardboard sheetmaterial intended for forming a box with a polygonal section comprising:side walls; a top wall linked to two of said opposite side faces by ajunction line; and one or more bottom walls forming the bottom of thebox, wherein the top wall is formed by a pair of flaps, a pair of ledgeportions, a lid with edges, or a wrap sheet that comprises at least twoportions each provided with an oblique substantially triangular panelbelonging partly to a side wall or to one of said edges, straddling thejunction between walls or wall and edge, and capable of forming a convexportion creating a part projecting from the top surface of the box whenthe box is formed, and the bottom comprises at least two portions with aperforated surface so as to complement said projecting parts when theyare formed, in line with the latter when the box is formed and arrangedin order to engage in the projecting parts of a box below.
 10. The blankor set of blanks as claimed in claim 9, wherein each portion capable offorming a convex portion has four sides, including two adjacent sidesthat are free or cut out from the top wall, the other two, oppositesides being, respectively, linked to the top wall by a first fold lineand to the side wall or to the edge of the lid by an oblique second foldline, and further comprises a third fold line that is oblique and has asummit common with the first and second fold lines, in order to form thetriangular or substantially triangular panel.
 11. The blank as claimedin claim 10, wherein the third fold line is curved.
 12. The blank asclaimed in claim 9, wherein the third fold line or the tangent to thesummit of the third fold line forms an angle beta with the junction lineof between 15° and 45°.